Syndapin bridges the membrane-cytoskeleton divide during furrow extension

BAR domain proteins can regulate ‘membrane reservoirs’ that provide surface area and buffer membrane tension. Syndapin is an F-BAR and SH3 domain containing protein involved in cytoskeletal remodelling and endocytosis. The Syndapin F-BAR domain is uniquely versatile compared to others in the family and can bend phospholipid membranes into tubules of various diameters and directly bind actin. The Syndapin SH3 domain can also interact with actin remodelling proteins and modulate cytoskeletal contractility. Pseudocleavage furrow extension in the syncytial division cycles of Drosophila embryos requires the homeostatic control of conserved processes that control plasma membrane tension and actin contractility. We find that Syndapin plays an important role in promoting pseudocleavage furrow extension. We propose a model involving roles for Syndapin in membrane dynamics and direct or indirect effect on the cytoskeleton to explain how it affects pseudocleavage furrow growth, independent of its role in endocytosis

F-BAR domain protein Syndapin regulates actomyosin dynamics during apical cap remodeling in syncytial Drosophila embryos

International audienceBranched actin networks driven by Arp2/3 interact with actomyosin filaments in processes such as cell migration. Similar interactions occur in the syncytial Drosophila blastoderm embryo where expansion of apical caps by Arp2/3-driven actin polymerization occurs in interphase, and cap buckling at contact edges by Myosin II to form furrows takes place in metaphase. Here, we study the role of Syndapin (Synd), an F-BAR domain-containing protein, in apical cap remodeling prior to furrow extension. We found that depletion of synd resulted in larger apical caps. Super-resolution and TIRF microscopy showed that control embryos had long apical actin protrusions in caps during interphase and short protrusions during metaphase, whereas synd depletion led to formation of sustained long protrusions, even during metaphase. Loss of Arp2/3 function in synd mutants partly reverted defects in apical cap expansion and protrusion remodeling. Myosin II levels were decreased in synd mutants, an observation consistent with the expanded cap phenotype previously reported for Myosin II mutant embryos. We propose that Synd function limits branching activity during cap expansion and affects Myosin II distribution in order to bring about a transition in actin remodeling activity from apical cap expansion to lateral furrow extension

Fly Cell Atlas: A single-nucleus transcriptomic atlas of the adult fruit fly

For more than 100 years, the fruit fly Drosophila melanogaster has been one of the most studied model organisms. Here, we present a single-cell atlas of the adult fly, Tabula Drosophilae , that includes 580,000 nuclei from 15 individually dissected sexed tissues as well as the entire head and body, annotated to >250 distinct cell types. We provide an in-depth analysis of cell type–related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types between tissues, such as blood and muscle cells, reveals rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the Drosophila community and serves as a reference to study genetic perturbations and disease models at single-cell resolution